1. Field of the Invention
The present invention relates to backlights for display panels, and more particularly to a backlight unit capable of reducing the number of backlight unit drivers in a liquid crystal display (“LCD”) device including the same, and a method of driving the LCD device.
2. Description of the Related Art
A liquid crystal display (LCD) typically includes an LCD panel, and a backlight unit to supply light to the LCD panel. The LCD panel displays an image by modulating the transmittance of the light supplied from the backlight unit.
A conventional backlight unit that uses a fluorescent lamp as a light source requires a high voltage and consumes high power. Light emitting diode (“LED’) based backlights have been used in recent years to reduce power consumption. LEDs are complex semiconductors that convert an electrical current into light. The conversion process is fairly efficient in that it generates little heat compared to incandescent or fluorescent lights. In this case, an LCD panel is divided into a plurality of display areas to improve the contrast ratio of a dark portion of the LCD panel. Such an LCD device includes a plurality of backlight unit drivers for driving the LEDs arranged in light emitting areas to drive a backlight unit having a plurality of light emitting areas.
FIG. 1 is a circuit diagram showing a backlight unit and a backlight unit driver according to the related art.
Referring to FIG. 1, a backlight unit includes at least one LED 5 per light emitting area. When a plurality of LEDs 5 are provided, the LEDs 5 are connected to each other in series. The LED 5 arranged in each light emitting area receives an LED driving voltage VLED from a backlight unit driver 6 to emit light. The backlight unit driver 6 adjusts the level and supplying time of the LED driving voltage VLED by modulating an input voltage VIN and/or a dimming signal DS so that luminance per light emitting area is adjusted.
To adjust the luminance of the LEDs formed in respective light emitting areas, a plurality of backlight unit drivers 6 should be provided. The number of backlight unit drivers 6 provided is typically equal to the number of the light emitting areas, to control the luminance of the LEDs. Thus manufacturing costs are increased and the size of the backlight unit driver 6 is increased.